The discovery of X-rays by Wilhelm Roentgen in 1895 changed the medical profession far more than its simple black and white image would suggest. The beams he used, higher in frequency than ultraviolet light but lower in frequency than gamma rays, revolutionized the medical profession, allowing physicians to see inside a patient’s closed body to more readily diagnose disease and injury, laying the foundation for diagnostic radiology.
Within six months of his discovery, surgeons on the battlefield were using X-rays to locate bullets in wounded soldiers. Since that time they have continued to be used—for non-invasive imaging in biomedicine, non-destructive testing of materials, security screening, and more. As the technology has advanced, so has the clarity and accuracy of X-rays.
Today, radiographic images, including X-rays, mammograms, and computed tomography (CT), help detect diseases like cancer in its early stages when treatment can be most effective. However, until now, all of those technologies have still rendered images in black and white. Even accounting for the remarkable advances in clarity in imaging since Roentgen, it can still be difficult to detect the difference between healthy tissue and abnormalities when an image is in shades of gray.
Now, a new technology called spectral (color) computed tomography, or spectral CT, installed at the University of Notre Dame, gives researchers a new reason to use the phrase “in living color.”
According to project leaders Ryan K. Roeder, Associate Professor of Aerospace and Mechanical Engineering, and Tracy C. Vargo-Gogola, Senior Lecturer in Biochemistry and Molecular Biology with Indiana University School of Medicine at South Bend and the Harper Cancer Research Institute, the spectral CT they are using, which is part of a collaboration between Notre Dame and MARS Bioimaging Ltd. (MBI), is the first commercially available preclinical system in the US. The MARS system is based on the next generation of X-ray detectors developed in collaboration with CERN, University of Canterbury, University of Otago, and other partners.
How It Works
Housed in the Notre Dame Integrated Imaging Facility (NDIIF), the MBI preclinical spectral CT scanner can detect up to eight X-ray energy channels simultaneously, allowing color assignment to specific molecular signatures for improved identification of abnormalities, such as tumors.
“The technology promises a transformation for biomedical imaging in general and cancer imaging in particular,” said Bradley Smith, the Emil T. Hofman Professor of Chemistry and Biochemistry, and director of the NDIIF.
While the scanner uses advanced Xray detector technology made possible by the Medipix3 detector chip developed at CERN, it is aided by nanoparticle contrast agents that Roeder’s lab has created to “target” molecular signatures associated with cancer and other diseases. Individual contrast agents and tissue types can be identified and assigned a specific color, resulting in a more complete picture than ever realized. (See Figure 1)
Roeder, Vargo-Gogola, and their team are presently investigating spectral CT contrast agents for molecular imaging with support from the National Science Foundation. In addition, the researchers are forming a close collaboration with the Kelly Cares Foundation and the Saint Joseph Health System to develop more accurate breast cancer detection methods using molecular imaging for women with dense breast tissue using various molecular imaging approaches, including spectral CT. While these efforts focus on breast cancer, work with this new molecular X-ray scanner is promising for the detection and treatment of many types of cancers, including ovarian, colorectal, lung, and metastatic disease.
“Spectral computed tomography (CT) scanning is really the next great enhancement of clinical CT quality,” said David P. Hofstra, administrative director of the Diagnostic Imaging and Therapy Division at Saint Joseph Health System in Mishawaka, IN. “It takes us beyond comparing the number of ‘slices’ to a discussion about fundamentally better and more clinically valuable imaging.
“Someday, spectral CT technology may allow altogether different types of contrast materials other than iodine, which we use currently. Different or targeted contrast agents may show important clinical findings that we can only begin to imagine currently.”
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